Comillas Pontifical University. Madrid (Spain)
September 21st, 2026
Summary:
Transport is the only major sector in the European Union that has not reduced its greenhouse gas emissions since 1990. While the energy supply, industry and buildings sectors have achieved substantial reductions since then, transport emissions have increased by 19%. This trajectory does not reflect a lack of regulatory ambition, but the structural difficulty of decarbonising a sector where demand is closely linked to economic activity and whose territorial, technological and social heterogeneity limits the effectiveness of uniform strategies. This thesis analyses how current analytical approaches tend to misrepresent several dimensions of transport dynamics: the territorial heterogeneity of demand, the technology adoption when infrastructure deployment is conditioned by economies of scale, the resilience to disruptions of the decarbonised system, and the distributional impacts of the transition costs.
Chapter three proposes a transferable methodology for disaggregating transport demand in linear optimisation models for energy system planning. Using metropolitan population density to cluster areas in terms of public transport supply, the methodology defines three categories of Functional Urban Areas, distinguishing urban from suburban demand and regional from long-distance transport, thus deriving nine demand segments. Applied to Spain, the aggregated model overestimates modal-shift potential by almost 56%, while demand disaggregation reduces average system costs by more than 16% and reveals substantial spatial variation, from EUR 0.09 to 0.68 per passenger-km.
Chapter four develops a fleet-level total cost of ownership framework in which the refuelling infrastructure costs are dependent on station capacity and utilization level, across representative mission profiles. For hydrogen fuel cell trucks, results show how economic viability depends heavily on infrastructure scale: below ten daily refuelling events, infrastructure costs can increase TCO by more than 50%, whereas larger fleets could achieve cost parity with diesel before 2040 in long-haul segments. These results highlight the potential risks associated with AFIR's distance-based infrastructure mandates. They also suggest that mechanisms for aggregating demand can be more effective than CAPEX subsidies in supporting infrastructure deployment.
Chapter five shows how decarbonisation relocates rather than eliminating vulnerabilities of the transport system, as electrification and alternative fuels introduce new energy supply chains. The Multi-System Dynamics framework is implemented in the openMASTER model to simulate upstream disruptions, and uses Scenario Discovery, based on three indicators: energy service not served, system cost and system CO2 emissions. Results indicate that reduced wind availability is the dominant source of vulnerability: shortfalls beyond approximately 15% can trigger increasing system stress, while beyond 35% service continuity deteriorates unavoidably. Electricity network failures rank second, whereas natural gas availability acts as a second-order determinant.
Chapter six develops GETRI (Generalised Expenditure on Transport Relative to Income), an integrated indicator that combines time and monetary costs and normalises them by household income. Applied to the Madrid Functional Urban Area and using anonymized mobile phone data, GETRI reveals a double penalty affecting low-income households in peripheral areas. Vulnerability to public transport is driven primarily by time costs, whereas vulnerability to private vehicles is driven mainly by monetary costs. Some peripheral areas are also found to face a modal trap that cannot be effectively addressed through price-based instruments alone.
Overall, transport decarbonisation requires analytical and policy instruments that adequately represent the spatial structure of demand, account for the interaction between vehicles and infrastructure, assess system resilience, and capture the distributional consequences of the transition. Together, the contributions of this thesis provide a more comprehensive framework for evaluating transport decarbonisation strategies and support the design of pathways that are efficient, equitable and robust.
Spanish layman's summary:
El transporte es el único sector de la UE cuyas emisiones han crecido desde 1990. Esta tesis mejora la representación de dinámicas clave del sector, como la demanda territorial, la escala de infraestructura, la resiliencia y los impactos distributivos, para diseñar estrategias de descarbonización.
English layman's summary:
Transport is the only EU sector whose emissions have risen since 1990. This thesis improves how key dynamics of the sector are represented, from territorial demand and infrastructure scale to system resilience and distributional impacts, to support the design of decarbonisation strategies.
Descriptors: Transportation systems technology, Power technology, Sectorial economics, Social problems - Social disorder
Keywords: Transport decarbonisation · Energy system modelling · Hydrogen trucks · Refuelling infrastructure · Energy system resilience · Transport poverty
Citation:
M. Pérez-Bravo, "Decarbonising Transport: Spatial, Distributional, and Resilience Dimensions of the Transition", PhD. dissertation, Comillas Pontifical University, Madrid, Spain, 2026.
